David Zinman is not a conductor who always digs deep for meaning. And yet in some ways it was very satisfying to hear him Thursday night guest-conducting the Philadelphia Orchestra. He's efficient and workmanlike. He can move the music along, which is beneficent when you're dealing with an ensemble like Philadelphia's, which would happily slow down at the end of every phrase.

And the opening of Barber's potent

Symphony No. 1

intimated that revelation might be in the cards all evening. Zinman freshened the music with urgent speed and a lean sound. The Barber in fact ended up being his strongest statement of three, bringing to it a point of view that never quite materialized in Wolfgang Sawallisch's readings.

But elsewhere his contributions were harder to discern. He was a perfectly able partner in Elgar's

Cello Concerto in E minor

. But the orchestra is every bit as important as the soloist in this piece, and it's not clear how dull it could have grown had Truls Mørk not been present.

Mørk, the Norwegian cellist who debuted with this orchestra at the Mann in 1996, is a fascinating musical personality. His sound was sinewy and penetrating in the opening, even bright at times. Then, in those incredibly moving, hushed seconds in the last movement haunted by a distant memory of second-movement material, he was a totally different player. His sound was present and steady, but grew more arresting while nearly disappearing.

Why are some listeners obsessed with this work? It's for moments like this, in which vulnerability renders a passage so delicate it threatens to vanish altogether.

Vivid characterization is what Zinman failed to do in Strauss'

Also sprach Zarathustra

. The outlines were there. But without stopping to detail what Nietzsche and Strauss might have meant with "great longing," "joys and passion" or any of the other human feelings called for in the piece's nine distinct sections, Zinman's view of the universe was a limiting experience.